Coreopsis, also known as tickseed and callipsis, is a genus of herb with more than 30 species. Although technically an herb, though, this member of the daisy family is most often planted as an ornamental. It has long-lasting yellow flowers, grows in thick stands like wildflowers and is exceedingly easy to care for. In fact, coreopsis grows wild in many areas of North America with no help at all. However, to keep your coreopsis looking attractive and blooming to its potential, a little pruning goes a long way.
Deadhead the coreopsis’ spent flowers as they fade in mid-summer. Visit the plant twice weekly or so and remove faded or dead flower heads. Grasp the flower head in one hand, and prune the flower’s stem back to roughly one centimeter above the first node (the swollen portion of the stem at its point of origin). This deadheading encourages the coreopsis to produce more flowers. In fact, if you deadhead regularly, you can stimulate coreopsis to produce flowers virtually all season long.
Prune the coreopsis down to ground level in late August or early September when all of the blossoms have faded. This hard prune stimulates the coreopsis to come back more vigorously next spring and extend its life. This hard prune does not have to be done every year, but works well to stimulate coreopsis that has not flowered as well as it did the previous year.
Water coreopsis deeply immediately after hard pruning. Use a gentle spray of water to moisten the top 6 to 8 inches of the soil. This deep watering helps the coreopsis better cope with the mild shock of a hard prune.